Heretofore, photoresists using polymer materials have been used in the manufacture of IC, LSI and the like as well as in various microfabrications. However, the photo-etching step using these polymer photoresists has the following drawbacks because the developing and rinsing treatments of the photoresist after the exposure are carried out by immersing in developing and rinsing solutions, each of which is determined according to the respective photoresist used. That is, strict quality control for the above treating solutions is required and great care must be taken in setting the treating conditions and as a result, the photo-etching step is lacking in reproducibility and stability; degradation of pattern precision is caused by swelling deformation; the automating of this step becomes disadvantageous; the waste liquor disposal can be a problem. Lately, dry etching technique using a gas plasma has been introduced into the production process of semiconductor devices but treatment with developing and rinsing solutions is unavoidable as long as the photo-etching step using the conventional polymer photoresists remains in the production process. Thus it cannot be denied that the production process has not become completely dry. Even in the field of electron lithography and X-ray lithography, the above mentioned drawbacks are unavoidable as long as the polymer resist is used.
On the other hand, there have hitherto been proposed pattern-forming materials and a method of forming patterns with such materials (U.S. Pat. No. 4,127,414, A. Yoshikawa et al.), wherein a radiation sensitive chalcogenide layer 4 consisting of an amorphous chalcogenide layer 2 and a thin silver layer 3 successively superimposed on a substrate 1, as shown in FIG. 1, is exposed to a light 6 through a mask 5 having a given pattern as shown in FIG. 2 or an accelerated corpuscular beam 7, such as electron beam or the like, according to a given pattern as shown in FIG. 3, whereby silver is diffused into the amorphous chalcogenide layer at the exposed areas to form silver-doped amorphous chalcogenide layers 21 corresponding to the given pattern, and then an etching treatment is carried out with a first etchant dissolving off silver as shown in FIG. 4 and further with an alkaline solution dissolving off the amorphous chalcogenide layer 22 containing no silver as shown in FIG. 5. This is based on the fact that the amorphous chalcogenide film is easily soluble in the alkaline solution but becomes insoluble in the alkaline solution after being doped with silver, so the silver-doped amorphous chalcogenide layers are left on the substrate according to the given pattern.
In general, the amorphous chalcogenide film has a strong resistance to various acid solutions. Therefore, the silver-doped amorphous chalcogenide layer 21 can be used as an etching mask for a third etching treatment with a third etchant etching the substrate, as shown in FIG. 6. Furthermore, when a fourth etching treatment is carried out with a fourth etchant dissolving off the silver-doped amorphous chalcogenide layer, the substrate can be processed according to a given pattern, as shown in FIG. 7. In this connection, it has also been proposed that the radiation sensitive chalcogenide layer 4 consisting of the amorphous chalcogenide layer and the thin silver layer superimposed thereon can be used as a photoresist and an electron-resist (or so-called inorganic resist) (U.S. Pat. No. 4,127,414, A. Yoshikawa et al.).
However, the pattern-forming step using such an inorganic resist includes the solution treatment as described above, so that the use of the inorganic resist has the inevitable drawbacks accompanying the solution treatment, just as with the conventional polymer resists.